Monday, May 28, 2012

On Friday I had the pleasure of talking to about 60 fifth graders from Robinson Elementary School in Redondo Beach. The school was having its annual “I am a Scientist!” Day which gets students excited about science through fun demonstrations and talks from members of the science community. The presentations this year included a wide-variety of topics such as the science of magic, science and engineering in a refinery, robotics, and matter and reactions. My talk was about physics. We learned that physics is the study of matter and energy, that matter is anything that takes up space and has mass, and that energy is the ability to do work. I told them that Einstein is regarded as the father of modern physics because he was able to relate matter and energy through his world-famous equation.

The air flow from the wing of this airplane is shown
by colored smoke rising from the ground. The swirl
at the wingtip traces the aircraft’s wake vortex.

Then we talked a bit about fluid mechanics, the study of fluids and the forces acting on them. As an example I talked about a program created by NASA and the Federal Aviation Administration in 1990 where they studied wake vortexes. The swirling airflow from the wingtip of an airplane is its wake vortex, which exerts a powerful influence on the airflow behind the plane. Because of wake vortex, the FAA requires aircraft to keep a minimum distance between each other when they land and take off. The goal of the program was to boost airport capacity by determining conditions under which planes could fly closer together. They studied wake vortexes using wind tunnels, flight tests and supercomputers in order to fully understand the phenomenon. Then they used what they learned to create an automated system that could predict changing wake vortex conditions at airports. For example, they confirmed that pilots don’t have to worry as much about wake vortex in rough weather because turbulent, windy conditions cause them to dissipate more quickly. Afterwards, we did a neat demonstration of how to create a vortex using a closed cardboard box with a circle cut out of the side and a fog machine. Everyone in the class was able to create a vortex and use it to knock over a stacked pyramid of styrofoam cups. It was a fun day and I was very impressed by how knowledgeable the kids were. Also, a big thanks to my daughter Daniella who was my capable assistant for the day. Hopefully we can do it again next year!

Tuesday, May 15, 2012

LCROSS mapping of the lunar south pole showing Cabeus and Shackleton craters, which have been found to contain ice.

There is water on the Moon—lots of it. Permanently-shadowed craters at both poles have been trapping and accumulating ice for billions of years, research has shown. These cold traps contain at least 600 million tons of ice according to research done over the last few years. Concentrated stores of ice on the Moon could revolutionize space travel. Lunar ice could be mined and split into its component elements hydrogen and oxygen to make rocket fuel, then brought to low Earth orbit and sold. An orbiting filling station could spur a wave of space travel because spaceships wouldn’t have to bring all the fuel they need from Earth. Considering that it costs about $10,000 to put one kilogram of payload into low earth orbit, there is a huge incentive to set up a mining camp on the Moon to tap these vast deposits of water to create a sustainable expansion into space. The lunar poles are unique because they have craters that never get a drop of sunlight, making them super cold. Shackleton crater, named after the famous Antarctic explorer Ernest Shackleton, is one that has been studied in detail. Situated at the Moon’s south pole, the interior of Shackleton crater is in permanent shadow. Also, the rim of this crater is in constant sunlight, making it an ideal location as a lunar outpost. Sunlight on the rim could provide energy for solar panels which in turn could provide the energy needed to harvest the water in the crater, and NASA is planning on setting up an outpost there by 2020. NASA’s Lunar Reconnaissance Orbiter (LRO) probed this impact crater with radar back in 2009. Shackleton crater was a good candidate because it is so massive—4.2 km deep and 21 km across, making it one of the deepest crater on the Moon. By analyzing the reflections off Shackleton crater, researchers discovered that is contains radar-transparent material which is consistent with ice.

Several other Moon missions have corroborated the existence of water on the Moon. In 2008, India’s Chandrayaan-1 spacecraft found evidence of water molecules on the lunar surface by deploying an impact probe onto the surface of the moon and then flying through the cloud of debris it kicked up. Chandrayaan-1 also mapped the moon with radar from 2008 to 2009 and found that the polar regions contained ice within the depths of permanently-shadowed craters. In 2009, the Lunar Crater Observation and Sensing Satellite (LCROSS) also discovered water and ice kicked up after an impact probe smashed into the Cabeus crater near the Moon’s south pole.

Monday, May 7, 2012

Scientists explore the world around us and make discoveries about the universe and how it works. Engineers then apply that knowledge to solve real-world problems, usually with the goal of optimizing cost and efficiency. In other words, if science is the discovery of what is possible, then engineering takes that knowledge and makes it economical. For example, a few weeks ago I wrote about a process for making eco-friendly cement. Researchers from George Washington University developed what they called Solar Thermal Electrochemical Production (STEP), which eliminates carbon dioxide from the cement-production process. The claim was that not only would it be more eco-friendly, but also less expensive than traditional methods. STEP would use solar energy in two ways. It would eliminate the needs for fossil fuels by using solar thermal energy to melt the limestone. It would also use solar energy to electrolyze the melt to produce lime (the main ingredient in cement), oxygen and carbon monoxide. Scientifically, a very interesting idea. But let’s play devil’s advocate and take a closer look with our engineering hardhat on. Even if something can be done experimentally, it's a far cry from being profitable in the short term. One drawback of the STEP process is that it adds complexity to the production of cement, which is rarely cost-effective. The research claims that by selling the carbon monoxide by-product, they could make $300 per ton of cement produced. I view this claim with suspicion. Carbon monoxide has a small and specialized market when sold by the bottle, so if this process was implemented broadly, the demand for this by-product would drop sharply. Most carbon monoxide that is currently needed is produced on-site to avoid shipping costs. Another point to consider is whether or not the STEP process could be portable. Most cement made today is produced by trailer-mounted units that are taken to the quarry and assembled in the field. By making the cement on-site it eliminates the need to transport tons of raw materials, especially for cement where it takes about five tons of raw materials to make one ton of finished product. It's hard to envision how a vast array of solar panels and mirrors could be transported and assembled efficiently. Another potential problem with solar power is that solar panels work best in a dust-free environment. Cement production creates a lot of dust and it would be difficult to keep the solar panels clean and operating at maximum efficiency. Also, it goes without saying that this process would not work too well in colder climates. One of the truths of scientific research is that much of it never ends up as part of a real production process. That’s just the nature of the game. But even if only one idea in a hundred is successful, it’s worth the price in my opinion. And even if an idea ends up not being feasible, sometimes it will lead to another discovery. Even plastic was invented by accident in an attempt to create a cheap substitute for shellac.